[lldb] Fix AppleObjCDeclVendor for classes which have no methods

[kastiglione]

Fix the rare case where an ObjC class has ivars but no methods. The fix is to not early
return when a class has no method list.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Dave Lee (kastiglione)

Changes

Fix the rare case where an ObjC class has ivars but no methods. The fix is to not early
return when a class has no method list.

---

Full diff: https://github.com/llvm/llvm-project/pull/145452.diff

6 Files Affected:

• (modified) lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp (+3-4)
• (added) lldb/test/API/lang/objc/class-without-methods/Makefile (+5)
• (added) lldb/test/API/lang/objc/class-without-methods/Point.h (+8)
• (added) lldb/test/API/lang/objc/class-without-methods/Point.m (+4)
• (added) lldb/test/API/lang/objc/class-without-methods/TestObjCClassWithoutMethods.py (+11)
• (added) lldb/test/API/lang/objc/class-without-methods/main.m (+9)

diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp
index dac93931bab1b..1c120fcf2c356 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp
@@ -552,10 +552,9 @@ bool ClassDescriptorV2::Describe(
     } else {
       std::optional<method_list_t> base_method_list =
           GetMethodList(process, class_ro->m_baseMethods_ptr);
-      if (!base_method_list)
-        return false;
-      if (!ProcessMethodList(instance_method_func, *base_method_list))
-        return false;
+      if (base_method_list)
+        if (!ProcessMethodList(instance_method_func, *base_method_list))
+          return false;
     }
   }
 
diff --git a/lldb/test/API/lang/objc/class-without-methods/Makefile b/lldb/test/API/lang/objc/class-without-methods/Makefile
new file mode 100644
index 0000000000000..f6f336c01bbc5
--- /dev/null
+++ b/lldb/test/API/lang/objc/class-without-methods/Makefile
@@ -0,0 +1,5 @@
+OBJC_SOURCES := Point.m main.m
+include Makefile.rules
+
+# Only objc metadata, no debug info, for Point.m
+Point.o: CFLAGS_EXTRAS += -g0
diff --git a/lldb/test/API/lang/objc/class-without-methods/Point.h b/lldb/test/API/lang/objc/class-without-methods/Point.h
new file mode 100644
index 0000000000000..85c0cd6c895b3
--- /dev/null
+++ b/lldb/test/API/lang/objc/class-without-methods/Point.h
@@ -0,0 +1,8 @@
+#import <objc/NSObject.h>
+
+@interface Point : NSObject {
+@public
+  float _x;
+  float _y;
+}
+@end
diff --git a/lldb/test/API/lang/objc/class-without-methods/Point.m b/lldb/test/API/lang/objc/class-without-methods/Point.m
new file mode 100644
index 0000000000000..eb5888e5b599f
--- /dev/null
+++ b/lldb/test/API/lang/objc/class-without-methods/Point.m
@@ -0,0 +1,4 @@
+#import "Point.h"
+
+@implementation Point
+@end
diff --git a/lldb/test/API/lang/objc/class-without-methods/TestObjCClassWithoutMethods.py b/lldb/test/API/lang/objc/class-without-methods/TestObjCClassWithoutMethods.py
new file mode 100644
index 0000000000000..587f22dedadf7
--- /dev/null
+++ b/lldb/test/API/lang/objc/class-without-methods/TestObjCClassWithoutMethods.py
@@ -0,0 +1,11 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestCase(TestBase):
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "break here", lldb.SBFileSpec("main.m"))
+        self.expect("frame var -P1 p", substrs=["_x = 11", "_y = 22"])
diff --git a/lldb/test/API/lang/objc/class-without-methods/main.m b/lldb/test/API/lang/objc/class-without-methods/main.m
new file mode 100644
index 0000000000000..f3241f46bbe5f
--- /dev/null
+++ b/lldb/test/API/lang/objc/class-without-methods/main.m
@@ -0,0 +1,9 @@
+#import "Point.h"
+
+int main() {
+  Point *p = [Point new];
+  p->_x = 11;
+  p->_y = 22;
+  // break here
+  return 0;
+}